Page 1 of 16 

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in 

discussions with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not 

final NIOSH or ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document 

represents preliminary positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed 

to identify and redact any information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution. 

Thorium In Vivo Coworker Study for Feed 

Materials Production Center (1979-89): A proposed 

attachment for ORAUT-TKBS-0017-5, Rev 2. 

White Paper 

Rev. 2 

National Institute for Occupational 

Safety and Health 

August 27, 2014 

Matt Arno, Tom LaBone, Bob Morris, and Billy Smith 

Oak Ridge Associated Universities Team 

-

Reviewed by Stu Hinnefeld and Mark Rolfes 

Division of Compensation Analysis and Support
 
2.0 THORIUM MIXTURES 

2.1 NATURAL THORIUM 

Natural thorium is composed of equilibrated Th-232 and Th-228 and their decay products as 

shown in Figure 1. Because the specific activity of Th-232 is small (1.1 x 10-7 Ci per g) 

compared to Th-228 (820 Ci per g) (ORNL 2006) essentially all of the mass in any thorium 

mixture is associated with Th-232. In 1.0 g of natural thorium there would be 1.0 g of Th-232 

and 13 ng of Th-228 (ORNL 2006). 

1.0 PURPOSE 

Some employees at DOE sites were not monitored for internal ionizing radiation exposure, or the 

records of such monitoring are incomplete or unavailable. In such cases, data from monitored 

coworkers can be used to estimate an individual’s possible exposure. The purpose of this paper 

is to provide monitored coworker information for calculating and assigning occupational internal 

doses to employees at the Feed Materials Production Center (Fernald) for whom no, or 

insufficient, monitoring records exist. 

The thorium intake rates developed in this coworker study are to be used for dose reconstruction 

for the period 1979 through 1989. During Fernald Working Group discussions, agreement was 

reached that the median of the coworker model would be used as a minimum value for intake 

rate regardless of the data in a worker’s internal dose record. This ensures that no in vivo count 

underestimates the intake rate due to a count being conducted shortly after chemical separation, 

before equilibration of Th-228 and Pb-212 can occur. 

Page	2	of	18

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution. 
This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions with the ABRWH oSubcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or ABRWH (or their technical support and review contractors) posmarked as such. This document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been 

redact any information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution. 
Figure 1. Natural thorium decay chain showing isotopes and half lives. Alpha decays are represented by vertic

decays are represented by horizontal arrows (ORNL 2006). This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions with the ABRWH o

Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or ABRWH (or their technical support and review contractors) pos

marked as such. This document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been redact any information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution. 
 This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution. 

Following a single chemical purification of natural thorium, the isotopic ratio of daughter 

products is disrupted and the degree of equilibrium changes as a function of time while ingrowth 

of daughters occurs, as illustrated in Figure 2. 

0 2 4 6 8 10 12 14 16 18 20 

0.01 

0.1 

1 

Activity Relative to Th-232 

Time (years) 

Th-228 total 

Th-228 unsupported 

Th-228 supported 

Ac-228 

Figure 2. Relative activity of the isotopes in the natural thorium decay chain as a function of 

time following chemical purification. All Rn-220 and decay products are assumed to be retained 

in the thorium material (ORNL 2006). 

One of the bounding scenarios examined in this coworker model assumes that the Th-232, Th228 and all daughters are in equilibrium. This is an extreme example that is unlikely to have 

occurred because natural thorium would have been processed after mining and prior to arrival at 

Fernald. Alternatively this scenario could be realized if the thorium had been refined two or three 

decades prior to processing at FERNALD. 

2.2 THORIUM USED FOR MIVRML CALIBRATION 

The Mobile In-Vivo Radiation Monitoring Laboratory (MIVRML) was calibrated using a 

thorium source described in a note published in Health Physics (Scott, L. M., 1966). This was 

confirmed by an interview with a subject matter expert (Smith 2012). The calibration source had 

an activity ratio of Th-232 to Th-228 of 1.27. In other words, the equilibrium between Th-228 

and Th-232 was 0.787. Because of the short half-life of Th-228 daughters, it is reasonable to 

assume that Th-228 and Pb-212 exist in equilibrium. Note that for this to occur, Rn-220, a noble 

gas which is an intermediate member of the decay chain, is assumed to remain in place. Since its 

half life is short, (56.6 s) this is a reasonable assumption, though not rigorously true [1]. 

Page	5	of	18
2.3 

Thorium material similar to this calibration source would have been chemically purified 

approximately 1 year prior to analysis and is deemed to be a realistic mixture, likely to be 

encountered during operations. 

TRIPLE-SEPARATION THORIUM 

Another bounding scenario considered involves a sequence of thorium purifications that are 

timed to produce the greatest possible reduction of the Th-228/Th-232 ratio (ORAUT 2014a). 

Because of its long half-life the activity of Th-232 does not change with time, but the activity of 

Th-228 decreases then increases as shown in Figure 3. The activity of both isotopes is assumed 

to be 1 Bq for illustration when chemical purification is completed. This is illustrated in a 

simpler depiction in Figure 3 below. 

0 5 10 15 20

0.1 

1 

Th-228 (Bq) 

Time (years) 

Th228 

Figure 3. Th-228 activity after a single chemical purification. The minimum occurs 4.55 years 

after purification. 

Th-228 Present After Separation 

For all practical applications Ra-224, with its short 3.66 day half life, is always in secular 

equilibrium with Th-228, but Ra-228, with 5.75 year half life, is depleted and takes years to grow 

back to any significant degree. The ingrowth curves for Ra-224 and Ra-228 are shown in Figure 

4. The minimum in the Ra-224 curve coincides with the minimum in the Th-228 curve. 

If we take the thorium source at 4.55 years and again strip off all of the daughters, we will have 

the Th-228 ingrowth curve shown in Figure 5, which has a minimum of 0.26 Bq at 2.54 years 

after the second separation (or 2.54 + 4.55 = 7.09 years after the first separation). The 

corresponding Ra-224 and Ra-228 curves following the second separation are shown in Figure 6. 

Page	6	of	18

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution. 
If we take this thorium source at 7.09 years after the first chemical separation and again strip off 

all of the daughters for the third time, we will have the Th-228 ingrowth curve in Figure 7, which 

has a minimum of 0.19 Bq at 1.75 years after the third separation (or 1.75 + 2.54 + 4.55 = 8.84 

years after the first separation). The corresponding Ra-224 and Ra-228 curves following the 

third separation are shown in Figure 8. 

Figure 4. Ra-228 and Ra-224 ingrowth after thorium chemical separation. 

Ra-228 & 224 Present After Separation 

0 5 10 15 20

0.1 

1 

Activity (Bq) 

Time (years) 

Ra224
 

Ra228
 

0 5 10 15 20

0.1 

1 

Th-228 (Bq) 

Time (years) 

Th228 

Th-228 Present After Separation 

Page	7	of	18

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution. 
0 5 10 15 20

0.1 

1

Activity (Bq) 

Time (years) 

Ra224
 

Ra228
 

Figure 6. Ra-224 and Ra-228 activity after a second chemical purification which occurred when 

Th-228 was at its lowest equilibration point (4.55 years) after the first purification. 

Th-228 Present After Separation 

0 5 10 15 20

0.1 

1 

Th-228 (Bq) 

Time (years) 

Th228 

Figure 5. Th-228 activity after a second chemical purification which occurred at its lowest 

equilibration point (4.55 years) after the first purification. The activity minimum is reached 7.09 

years after the first purification. 

Ra-228 & 224 Present After Separation 

Page	8	of	18

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution. 
 This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution. 

0 5 10 15 20

0.1 

1 

Activity (Bq) 

Time (years) 

Ra224
 

Ra228
 

Figure 8. Ra-224 and Ra-228 activity after the third chemical separation. 

3.0 

Figure 7. Th-228 activity after a third chemical purification which occurred when at its lowest 

equilibration point (7.09 years) after the first purification. The activity minimum, 0.19 Bq, is 

reached 8.84 years after the first purification. 

Ra-228 & 224 Present After Separation 

In summary, this scenario results in the equilibrium ratio between Th-232 and Pb-212 reaching a 

minimum value of 0.19. This chronic intake analysis assumes that all of the activity inhaled 

always has this most pessimistic isotopic makeup, i.e., this scenario results in the highest intake 

rates and thus is most claimant favorable. 

DATA AND METHOD OVERVIEW 

Analysis of Coworker Bioassay Data for Internal Dose Assignment (ORAUT 2005) describes the 

general process that is used to analyze bioassay data for assigning doses to individuals based on 

coworker results. Coworker Data Exposure Profile Development (ORAUT 2004) describes the 

approach and processes to be used to develop reasonable exposure profiles based on available 

dosimetric information for workers at DOE sites. 

The Y-12 MIVRML was used at Fernald from 1968 through 1989. Prior to its use at Fernald, the 

MIVRML system and its use were described in a management memorandum to all employees 

(Heatherton no date). The memo explains that those workers with the highest uranium and 

thorium exposure potential would be counted most frequently and those with virtually no 

exposure potential would not be routinely counted at all. Workers identified to have potential 

Page	9	of	18
exposures to thorium were given priority for counting during the first use of the MIVRML (Rich 

2007) [2]. 

The technology and challenges associated with in vivo counting for thorium were described by 

West (1962 and 1965). An interview with the lead analyst for the MIVRML at Fernald was 

conducted (Smith 2012) and provided additional specific details on the calibration and operation 

of the system while at Fernald. 

3.1 DATA SELECTION 

Hand-written records of in vivo chest count data for individual Fernald workers were obtained 

(NLO 1968 through 1988). The great majority of the entries in these records represent data 

obtained between 1968 and 1988 using the MIVRML. Data from these records from 1979 

through 1988 were transcribed into a spreadsheet and validated as described by Morris (2006). 

A total of 2,994 records in this time interval were transcribed. This represented data on 

approximately 1,000 individuals. Most results were reported as "Pb-212” and “Ac-228" 

activities; only the Pb-212 data was used since it is most indicative of a thorium intake (ORAUT 

2014a). 

The ORAU Team Principal Internal Dosimetrist reviewed the transcribed data. This review 

yielded a number of modifications and exclusions from the statistical analysis. The reasons for 

exclusion included: 

 Results labeled “AEC/ERDA/DOE recount program.” 

 Control samples. 

 Those indicated to be “bad samples” or "unreliable.” 

 Entries with no results. (Most of these appear to have been counts that were scheduled 

but not performed; comments included “claustrophobic,” “off sick,” and “count was 

canceled because of high background problems.”) 

Samples indicated to be recounts or duplicates were averaged into a single result for the given 

date or sample. 

3.2 STATISTICAL DESCRIPTION OF DATA 

The chest count data were statistically evaluated using yearly intervals according to the 

specifications and requirements in ORAUT 2006 and ORAUT 2014b using the Time Weighted 

One Person One Statistic (TWOPOS) methodology. In vivo chest count data statistics were 

generated for each analysis interval. The Pb-212 chest counts were determined to be biased, so a 

bias correction factor was subtracted from each individual chest count as given in Table 1. 

A lognormal distribution was assumed [4] and the 50th- and 84th-percentile values were 

calculated. All calculations were independently repeated for validation. The values were 

Page	10	of	18	

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution. 
converted to Th-232 lung burdens by dividing by 0.19 as discussed above. Table 2 presents the 

annualized results of the statistical analysis for Th-232 in nCi. Figure 9 shows plots of the 50th 

and 84th percentile chest burden. 

Table 1. Bias for Pb-212 (nCi) in Chest [3] 

Year Pb-212 Bias 

1979 -0.014 

1980 -0.045 

1981 -0.056 

1982 -0.058 

1983 -0.101 

1984 -0.089 

1985 -0.086 

1986 -0.085 

1987 -0.047 

1988 0.002 

Table 2: Fernald in vivo lung counting statistics and Th-232 lung burdens. 

Year 

Effective 

Bioassay 

Date 

# of 

TWOPOS 

results 

50th percentile 

(nCi) 

84th percentile 

(nCi) 

1979 6/30/1979 124 0.039 0.129 

1980 6/30/1980 149 0.032 0.116 

1981 6/30/1981 129 0.035 0.121 

1982 6/30/1982 167 0.054 0.147 

1983 6/30/1983 167 0.036 0.120 

1984 6/30/1984 322 0.042 0.107 

1985 6/30/1985 355 0.041 0.103 

1986 6/30/1986 433 0.037 0.103 

1987 6/30/1987 523 0.038 0.097 

1988 6/30/1988 108 0.045 0.104 

Page	11	of	18	

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution. 
nCi Pb‐212

0.160

0.140

0.120

0.100

0.080

0.060

0.040

0.020

0.000

1979 1980 1981 1982 1983 1984 1985 1986 1987 1988
 

Year

50th 84th

Figure 9. 50th and 84th percentile Th-232 chest burdens for the period 1979 through 1988. 

4.0 INTAKE MODELING 

Results from the statistical analyses, adjusted to represent Th-232 activity in pCi as discussed 

above, were used to determine thorium coworker intake rates. The biokinetic model described in 

ORAUT-OTIB-0076 (ORAUT 2014a) was used to fit the in vivo measurement data associated 

with thorium isotopes to a series of chronic inhalation intakes for both types M and S. 

A single chest count result for each period was assumed to have occurred at the midpoint of the 

period. A uniform absolute error of 1 was applied to all results, which thus assigned the same 

weight to each result. The intake assumptions were based on patterns observed in the in vivo 

data. A single constant chronic intake rate was chosen due to the consistent magnitude of the 

chest counts. 

The resulting coworker thorium intake data are shown in Table 3. Geometric standard deviation 

(GSD) values are equal to the 84th percentile intake rates divided by the 50th percentile intake 

rates. To account for the error in biokinetic modeling, a minimum GSD value of 3.00 is assigned 

because that is the assumed GSD for an individual who was monitored. The data for 1980 

through 1988 are extrapolated to include 1989 [5]. Figures 10 through 13 illustrate the result of 

coworker intake modeling for thorium. 

Page	12	of	18	

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution. 
Pb‐212 Chest Burden (pCi)

60

50

40

30

20

10

0

1979 1980 1981 1982 1983 1984

Year

1985 1986 1987 1988
 

Figure 10. Predicted thorium lung burden (line) calculated using the three 

separation model to derive thorium intake rates compared with measured 

chest burden (dots), 1979-1989, 50th-percentile, Type M. 

Table 3. Derived thorium intakes, 1979 through 1989 

Intake Solubility 

Type 

50th percentile 

(pCi/day) 

84th percentile 

(pCi/day) 

GSD 95th percentile 

(pCi/day) 

Type M 41.38 119 3.00 252 

Type S 6.26 17.0 3.00 38.1 

160

140

Pb‐212 Chest Burden (pCi)

120

100

80

60

40

20

0

1979 1980 1981 1982 1983 1984 1985 1986 1987 1988

Year

Page	13	of	18	

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution. 
60

Pb‐212 Chest Burden (pCi)50

40

30

20

10

0

Year

1979 1980 1981 1982 1983 1984 1985 1986 1987 1988
 

Figure 12. Predicted thorium lung burden (line) calculated using the three 

separation model to derive thorium intake rates compared with measured 

chest burden (dots), 1979-1989, 50th-percentile, Type S. 

160

140

Pb‐212 Chest Burden (pCi)

1979 1980 1981 1982 1983 1984 1985 1986 1987 1988
 

120

100

80

60

40

20

0

Year

Figure 13. Predicted thorium lung burden (line) calculated using the three 

separation model to derive thorium intake rates compared with measured 

chest burden (dots), 1979-1989, 84th-percentile, Type S. 

Figure 11. Predicted thorium lung burden (line) calculated using the three 

separation model to derive thorium intake rates compared with measured 

chest burden (dots), 1979-1989, 84th-percentile, Type M. 

Page	14	of	18	

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution. 
 

5.0 ANNOTATION AND ATTRIBUTION 

[1] LaBone, Thomas. ORAU Team, Deputy Principal Internal Dosimetrist, December 18, 2007. 

The assumption of equilibrium between Pb-212 and Ra-224 requires an assumption that none of 

the noble gas Rn-220 escapes the lung. Rn-220 has a half-life of only 55.6 s which makes this a 

reasonable assumption. 

[2] Morris, Robert. MH Chew & Associates, Inc. Principal Health Physicist. November 14, 

2007. 

Inspection of in vivo monitoring records confirms that many of the workers counted during the 

first visit had "thorium worker" or "former thorium worker" noted on their individual MIVRML 

log sheets. 

[3] Kent, Karen. ORAU Team. Dose Reconstructor. May 19, 2014. 

Bias factors are based on the Fernald Post SEC Thorium Methodology developed as part of the 

SEC evaluation. 

[4] Arno, Matthew. ORAU Team. Dose Reconstructor. June 18, 2007. 

Lognormal distributions typically provide the best fit to the available data and are a distribution 

suitable for input into IREP. 

[5] Morris, Robert. MH Chew & Associates, Inc. Principal Health Physicist. November 14, 

2007. 

The FEMP SEC petition includes 1989. The thorium operations in 1989 were unchanged from
 

those in 1988 and it is judged reasonable and efficient to extend the 1980 through 1988 period to 

include 1989. 

Page	15	of	18	

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

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ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution. 
 This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution. 

6.0 REFERENCES 

Heatherton, R. C., no date, memorandum to "All NLO Employees" regarding NLO IN VIVO 

COUNTING PROGRAM, SRDB Ref ID 2932 

ICRP (International Commission on Radiological Projection, 1995, Dose Coefficients for Intake 

of Radionuclides of Workers, Publication 68, Oxford, England, June. 

Morris, R. L., 2006, Transcription of Fernald MIVRML Data, November 12, 2006, SRDB Ref 

ID 27643 

NLO (National Lead of Ohio), 1968 through 1988, In Vivo Counting Results, SRDB Ref ID 

numbers 26774, 26777, 26780, 26781, 26782, 26783, 26784, 26785, 26786, 26787, 26788, 

26789, 26790, 26791, 26792, 26793, 26794, 26795, 26796, 26797, 26798, 26813. 

ORAUT (Oak Ridge Associated Universities Team), 2004, Coworker Data Exposure Profile 

Development, ORAUT-PLAN-0014, Rev. 00, Oak Ridge, Tennessee, November 24. 

ORAUT (Oak Ridge Associated Universities Team), 2005, Technical Information Bulletin: 

Analysis of Coworker Bioassay Data for Internal Dose Assignment, ORAUT-OTIB-0019, Rev. 

01, Oak Ridge, Tennessee, October 7. 

ORAUT (Oak Ridge Associated Universities Team), 2006, Procedure: Generating Summary 

Statistics for Coworker Bioassay Data, ORAUT-PROC-0095, Rev. 00, Oak Ridge, Tennessee, 

June 5. 

ORAUT (Oak Ridge Associated Universities Team), 2014a, Guiding Reconstruction of Intakes 

of Thorium Resulting from Nuclear Weapons Programs, ORAUT-OTIB-0076, Rev. 00, Oak 

Ridge, Tennessee, July 10. 

ORAUT (Oak Ridge Associated Universities Team), 2014b, Analysis of Stratified Coworker 

Datasets, ORAUT-RPRT-0053, Rev. 01, Oak Ridge, Tennessee, Draft. 

ORNL (Oak Ridge National Laboratory), 2006, Radiological Toolbox User's Manual. 

ORNL/TM-2004/27R1, software version 2.0.0, Oak Ridge, Tennessee, August 31, 2006. 

Rich, B. L., 2007, Interview, line number 920 ff, SRDB Ref ID 38124, August 30. 

Smith, B. P., 2012, Interview, SRDB Ref ID 110639, March 15. 

Scott, L. M., 1966, A Technique of Assessing Thorium Body Burdens Utilizing In Vivo Gamma 

Spectrophy, Health Physics, Vol. 12, pp 101-103. 

Page	16	of	18	
West, C. M, 1962, An evaluation of the health physics problems from thorium and its daughters 

in a thorium purification and fabrication process, Health Physics, Vol. 8, pp 279 - 297. 

West 1965, "Health Physics Considerations associated with Thorium Processing," Y-KB-53 

Union Carbide Corporation Nuclear Division, Oak Ridge, TN, March 10. SRDB Ref ID 11596. 

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information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.